Dross is a byproduct of soldering processes, such as wave soldering. Dross includes oxides of the metals of which the solder is composed, contaminants which come from flux and/or other agents used in the soldering process, and some usable solder. In particular, during oxidation, nuclei of solder are formed which are enveloped by oxides. Clusters of such units form the dross. Dross can disrupt the soldering process.
Dross has a density that is less than that of solder so that dross typically floats on molten solder. Known methods of dealing with dross include scooping the dross off the surface of molten solder. However, when the dross is scooped away, not only are metal oxides and contaminants removed, but also some usable solder.